From the Guidelines
Thrombocytosis is primarily caused by either essential thrombocythemia (ET) or reactive thrombocytosis.
Causes of Thrombocytosis
- Essential Thrombocythemia (ET): a myeloproliferative neoplasm characterized by sustained platelet count ≥ 450 × 10^9/L, bone marrow biopsy showing megakaryocytic proliferation, and absence of other myeloid neoplasms 1.
- Reactive Thrombocytosis: caused by iron deficiency, splenectomy, surgery, infection, inflammation, connective tissue disease, metastatic cancer, and lymphoproliferative disorders 1.
Key Factors
- JAK2 V617F mutation: present in some ET patients and contributes to thrombotic tendency 1.
- Leukocytosis: confers a 60% increase in thrombotic risk in ET patients 1.
- Age and thrombosis history: significant risk factors for thrombosis in ET patients 1.
- Cardiovascular risk factors: such as smoking, hypertension, and diabetes mellitus, also contribute to thrombotic risk in ET patients 1.
From the Research
Causes of Thrombocytosis
Thrombocytosis can be caused by various factors, including:
- Primary thrombocytosis, which is a clonal disease associated with myeloproliferative disorders such as essential thrombocythemia, polycythemia vera, and primary myelofibrosis 2, 3, 4, 5
- Secondary or reactive thrombocytosis, which is a response to underlying conditions such as infection, chronic inflammation, iron deficiency, tissue damage, cancer, or surgical procedures 3, 4, 6
- Familial thrombocytosis, which is a rare genetic disorder 3, 5
Classification of Thrombocytosis
Thrombocytosis can be classified as:
- Mild: platelet count between 500,000/μL and 700,000/μL 3
- Moderate: platelet count between 700,000/μL and 900,000/μL 3
- Severe: platelet count greater than 900,000/μL 3
- Extreme: platelet count greater than 1,000/μL 3
Underlying Conditions Associated with Thrombocytosis
Various underlying conditions can cause thrombocytosis, including: